$word_{count}$: 280

Potential: V = $\frac{kQ}{r}$ (point charge). V = kp*cos$\frac{theta}{r}$^2 (dipole). $V_{ring}$ = $\frac{kQ}{sqrt}$(x^{2+R}^2). $V_{sphere}$(inside solid) = kQ$\frac{3R^2-r^2}{(2R^3)}$. $V_{sphere}$(inside hollow) = $\frac{kQ}{R}$.

E-V relation: E = -dV/dr. E = -grad(V). $V_A$ - $V_B$ = -integral from A to B of E.dr. For uniform field: V = -Ed + C.

Potential energy: U = $\frac{kq1q2}{r}$ (two charges). $U_{system}$ = sum over all pairs. W = q*delta(V). Number of pairs = N$\frac{N-1}{2}$.

Self-energy: Solid sphere: 3kQ^$\frac{2}{5R}$. Shell: kQ^$\frac{2}{2R}$.

Capacitance: C = $\frac{Q}{V}$. Parallel plate: C = $epsilon_0$A/d. With dielectric: C = K$epsilon_0$A/d. Spherical: C = 4pi*$epsilon_0$$\frac{ab}{b-a}$. Cylindrical: C = 2pi*$epsilon_0$L/ln$\frac{b}{a}$. Isolated sphere: C = 4pi*$epsilon_0$*R.

Combinations: Series: 1/$C_{eq}$ = sum$\frac{1}{C_i}$. Parallel: $C_{eq}$ = sum($C_i$). Two in series: C1*$\frac{C2}{C1+C2}$.

Energy: U = \frac{1}{2}$$CV^2 = $\frac{1}{2}$QV = Q^$\frac{2}{2C}$. Energy density: u = $\frac{1}{2}$$epsilon_0$$E^2$.

Dielectric (battery on): V same, C -> KC, Q -> KQ, U -> KU. Dielectric (battery off): Q same, C -> KC, V -> V/K, U -> U/K.

Redistribution: $V_f$ = $\frac{C1V1 + C2V2}{(C1+C2)}$. $U_{lost}$ = C1C2(V1-V2)^$\frac{2}{2(C1+C2}$).

Force between plates: F = Q^$\frac{2}{2*epsilon_0*A}$. Pressure: P = sigma^$\frac{2}{2*epsilon_0}$.

Partial dielectric: Series model C = $epsilon_0$$\frac{A}{d-t+t/K}$. Conducting slab: C = $epsilon_0$$\frac{A}{d-t}$.

Key constants: k = 9 x 10^9 N $m^2$/$C^2$. $epsilon_0$ = 8.854 x 10^(-12) F/m. 1 eV = 1.6 x 10^(-19) J.